The death toll was 12 dead with another 18 reported injured as of midday Moscow time. The first blast went off in the town of Kizlyar that is on the border with neighbouring Chechnya, a law enforcement source told Russian news agency RIA Novosti.

He said at least one blast was triggered by a suicide bomber dressed as a policeman. The first blast occurred at 08:45 Moscow time [04:45 GMT], and the second came 20 minutes later. A local police source said the disguised suicide bomber approached police who were working at the site of the first explosion and blew himself up.

Like the blasts in Moscow these were clearly intended to carry a political message and symbolise a strike at the central authorities. The explosions occurred some 300 meters from the buildings of the Interior Ministry, Federal Security Service and a school.

"According to preliminary information, a Niva car stuffed with explosives blew up. When police and emergencies services came to the site, a second blast went off," the source said.

Today is a national day of mourning in Russia following the first terrorist attack on themetro system in six years. The last attack in the Russian capital happened in August 2004 at the Paveletskaya metro station and killed 41, injuring hundreds of people.

Dagestan is a southern republic on the shores of the Caspian Sea and in the epicentre of the unstable Caucasus region. While Chechnya has been relatively peaceful following the end of the second Chechen war, it is far from normal. Dagestan was been unstable for years with bombings and shootings a regular occurrence. Neighbouring Ingushetia has experienced similar attacks. And Nalchik, the first major town in Russia proper in the region has been experiencing attacks involving dozens of people almost weekly.

The Moscow attacks are believed to have been committed by terrorists from Russia's North Caucasus region.